1. Field of the Invention
Ketoalkynoic acids and their esters that have the structural formula, ##STR1## wherein and elsewhere in this specification n is an integer of the set 1-8 and R is hydrogen atom or an alkyl group of 1-3 carbon atoms, are starting materials or intermediates in the synthesis of 2-(substituted)-cyclopentane-1,3,4-triones and their esters that have the general structure, ##STR2## Compounds II have anti-ulcerogenic properties (U.S. Pat. No. 3,558,682 [1971]) and utility as intermediates in the synthesis of prostaglandin E.sub.2 and its analogues (Heather et al., Tetrahedron Letters, No. 25, 2315 [1973]; hereafter "Heather").